Lower and Upper Ionosphere of Mars

The ionosphere of Mars has been explored mostly with the radio occultation experiment onboard Mariners 6, 7, 9; Mars 2, 3, 4, 6; Viking 1, 2, and more recently on Mars Global Surveyor (MGS) and Mars Express (MEX). In addition to the radio occultation experiment, MEX also carried Mars Advanced Radar for the Subsurface and Ionosphere Sounding (MARSIS) experiment which provided electron density profiles well above the main ionospheric peak. The atmosphere of Mars was measured directly by the neutral mass spectrometer onboard Viking 1 and 2 Landers. Later, an accelerometer and radio occultation experiment on MGS provided large data sets of atmospheric density at various locations in the upper and lower atmospheres of Mars, respectively. In this paper we review results of these upper and lower atmospheric/ionospheric measurements. Results of these measurements have been compared with theoretical models by several workers; therefore, we also review various atmospheric and ionospheric models of Mars.     

无人机航迹规划技术研究及发展趋势

通过对无人机航迹规划的研究,构建了无人机航迹规划的结构框架;分析了无人机系统约束及威胁场约束,探讨了无人机航迹几何建模方法及规划算法的国内外研究概况;并着重分析了规划算法。最后,阐述了无人机航迹规划面临的关键问题及发展趋势。     

对接综合试验台轨迹规划算法研究

为实现模拟空间两飞行器对接动力学过程的对接综合试验台的平稳对接，提出了一种基于加速度控制的轨迹规划算法。给出了不同初始条件下的规划方法，以及时转动自由度的特殊处理。物理试验结果表明，规划模型能精确控制平台从初始零位运动到主被动对接机构初次接触位置，且最后时刻平台姿态与对接试验的初始条件完全吻合。该算法可直接用于对接综合试验台的控制。     

Space Tweetup – from a participant to a Mars Tweetup organizer and a new format of space communication

In September 2011, the European Space Agency (ESA) and the German Space Agency (DLR) organized the first European SpaceTweetup during the German Aerospace day. One of the authors was one of 60 participants at this SpaceTweetup in Cologne and experienced the concept of a Tweetup and the engagement of the participants from the inside view.     

加工复杂零件的高端技术

瑞士加工中心制造商威力铭-马科黛尔公司着重于质量和生产效率,主要活跃于航空/航天、精密机械、钟表和医疗行业,并以其为用户提供的高性能交钥匙解决方案而著称.     

对接综合试验台控制系统软件快速原型开发技术

对基于快速原型设计睁对接综合试验台控制系统软件开发进行了研究。介绍了根据系统方案进行的中央控制台软件设计和模型计算机软件开发等。给出了快速原型设计,以及包括接口设计、配置管理、文档管理等软件工程化管理等关键技术。     

Schumann resonance frequency and conductivity in the nighttime ionosphere of Mars: A source for lightning

We have solved the Maxwellian equations of electromagnetic waves which oscillate within the cavity formed in the lower ionosphere of Mars between 0 and 70?km. The electrical conductivity and Schumann Resonance (SR) frequencies are calculated in the lower ionosphere of Mars, in the presence of a major dust storm that occurred in Martian Year (MY) 25 at low latitude region (25°–35°S). It is found that the atmospheric conductivity reduced by one to two orders of magnitude in the presence of a dust storm. It represents a small dust layer at about 25–30?km altitudes where lightning can occur. We also found that the SR frequencies peak at?～18?km with values 19.9, 34.5 and 48.8?Hz for the modes l?=?1, 2 and 3, respectively, in the non-homogeneous medium. Our results indicate that practical or measurable values of SR are dependent on the altitudes.     

Consequences of cometary aurora on the carbon chemistry at comet P/Halley.

Various experimental data acquired during the visit of Halley's comet in 1986 have shown that the amount of carbon produced due to photodissociation of parent carbon bearing species is not ample enough to explain the observations. This requires the presence of an additional source of atomic carbon. One of the possible source could be auroral-type activities resulting from the precipitation of high-energy "auroral electrons" of solar wind origin, the evidence of which have been inferred from many observations at comet Halley. We have developed a coupled chemistry-transport model to study the role of auroral and photoelectron impact as well as of chemistry on the modelling of carbon in the inner coma (< or = 10(4) km) of comet Halley. Our study suggest that electron impact dissociation of CO is the major source of carbon production in the inner coma, not the recombination of CO+ as suggested by earlier workers, while transport is the main loss process.     

Heusler合金M2CoA(M=Mn,Ti;A=Al,Si)的第一性原理

采用基于密度泛函理论(DFT)的第一性原理计算方法,研究了M₂CoA型Heusler合金Mn₂CoAl、Mn₂CoSi、Ti₂CoAl和Ti₂CoSi的电子结构和磁学性质。发现Heusler合金Mn₂CoAl是亚铁磁性自旋无带隙半导体,Mn₂CoSi与Ti₂CoAl是亚铁磁性自旋半金属,而Ti₂CoSi是铁磁性自旋半金属。它们的总自旋磁矩均为整数,符合Slater-Pauling规则。然后,在分析电子能带结构和态密度的基础上,探讨了自旋无带隙半导体与半金属性的根源。最后,声子谱和弹性常数计算结果表明所有M₂CoA型Heusler合金在晶格动力学和力学上均是稳定的。